The present invention concerns a process for the production of a multi-layer assembly for production of an electrochemical generator with low thickness. It also relates to the multi-layer assembly obtained, and also to production of the complete generator. It is particularly applicable to the production of generators in which the electrolyte is solid and comprised of an ion compound dissolved in an elastomer macromolecular material. The principle of these polymer electrolyte generators is well known to a person skilled in the art, it is particularly described in the French patent published under No. 2 542 322 and entitled: "Macromolecular Material with Ion Conduction Comprised of a Salt in Solution in a Copolymer." Such generators, according to the prior art, are comprised of a positive electrode, an electrolyte and a negative electrode, these three elements being sandwiched between two metallic collectors.
As indicated in the French patent published under No. 2 442 514, the interesting aspect of these generators according to the prior art essentially rests in the fact that they form an elementary multi-layer assembly, in which each of the layers is flexible, has a very low thickness (&lt;80 microns), and adheres strongly to the adjacent layers, the overall thickness of the elementary multi-layer assembly generally being between 30 and 300 microns.
To prepare generators with high energy capacity which use relatively large surfaces, one must produce either stacked or coiled or even various folded forms of such elementary multi-layer assemblies.
In the case of coils or folds, the elementary multi-layer assemblies are subjected to major bending stress. It is known that in order to fold or bend two non-ductile superimposed films without damage, it is necessary that the two films are able to glide relative to one another at the folds or bends. If the two non-ductile films are made into a unit by means of an adhesive, even if it is elastic and only a thin layer, major restrictions are produced at the fold or bend, which result either in rupture of the exterior film or wrinkling of the interior film.
In the case of thin-film electrochemical generators, in other words generators formed of the aforementioned elementary multi-layer assembly, rupture of one of the layers as well as folding of the other results in destruction of the generator, either by rupture of the contact or by a permanent short circuit.